1. Field of the Invention
The present invention relates to a lighting apparatus having a white light source and a plurality of color light sources.
2. Description of the Related Art
There are two methods for displaying the desired color temperature in a liquid crystal display apparatus. With the first method, a backlight apparatus is configured by using a white light source and a color temperature is adjusted by image signal processing. With the second method, a backlight apparatus is configured using a plurality of primary color light sources, such as red, green, and blue light sources, and these primary color light sources are turned on at a light intensity ratio representing the desired color temperature and additive color mixing is performed.
Among these two methods, in the method in which the backlight apparatus is configured using only a white light source, the light emission efficiency is excellent, but the display color gamut is narrowed. Meanwhile, in the method in which the backlight apparatus is configured by using a plurality of primary color light sources, the display color gamut can be expanded, but since the light emission efficiency of each light source is low, energy consumption is difficult to decrease. Accordingly, a method can be considered in which the backlight apparatus is configured using a white light source and a plurality of primary color light sources and both a wide display color gamut and a highlight emission efficiency can be obtained by turning on the white light source and primary color light sources at a light intensity ratio at which the desired color temperature is realized.
Japanese Patent Application Publication No. 2001-351425 discloses a backlight apparatus in which a white fluorescent tube, a red fluorescent tube, a green fluorescent tube, and a blue fluorescent tube are disposed at both sides in the length direction of a light guide plate, and the white fluorescent tube is disposed at a position that is the closest to the light guide plate. With the backlight apparatus disclosed in Japanese Patent Application Publication No. 2001-351425, the decrease in light intensity and variation in color balance caused by deterioration of the fluorescent tubes can be corrected by adjusting the light intensity of each fluorescent tube.
Further, Japanese Patent Application Publication No. 2005-243347 discloses a backlight apparatus in which a plurality of light sources are arranged equidistantly, the emission color differs among the light sources adjacent in the arrangement direction, and outgoing illumination light is obtained by mixing lights emitted from the plurality of light sources. In the backlight apparatus disclosed in Japanese Patent Application Publication No. 2005-243347, at least one light source for which the emission color is that of illumination light is disposes so as to be the closest to the side wall.